Saturday, June 7, 2014

The Future of Residential Heat Recovery is Ductless

1. The 16cfm mode, medium, (perfect for a 2 person bedroom) is only 0.3 sones at 4 watts. Almost inaudible.

2. Low speed is 8cfm (the one person setting) is 0.1 sones which is TOTALLY inaudible.

3. It can cycle on humidity if desired. That is, it will come on when the humidity reaches 45%RH (low), 55% (medium), or 65% (high). If the indoor humidity exceeds the set point, the unit is switched to high speed. If the indoor humidity is within 5% of the set point, the unit operates at medium. If humidity is 5% below the set point, the unit switches to minimum speed. This sounds like a reasonable control strategy for winter, but in the dry Mountain West, it would always be on low speed. It sounds like the wrong control strategy for summer.

4. It pretty much is a ripoff of the Lunos design, but I don't know if either design is patented anyway.It's not synchronized like the Lunos but I believe synchronization is unnecessary, and actually reduces the total house airflow.

5. The US distributor, Zoltan, will give a quantity discount, which gets it down to a price I can justify in new construction spec homes and rentals. With a name like that, he knows all about predicting the future

6. The exterior vent cover is an elaborate, good looking, bomb proof fabrication of stainless steel.7. When the unit is off, it has a high quality, very tight powered plastic damper.In my opinion, if the bedroom doors are left open except at bedtime, Fick's Law of Diffusion will ensure that fresh air will reach the rest of the house. (The average speed of an air molecule flying around the room is 500m/s) That means a three bedroom house may only need 3 total units.Other important things that should be mentioned:A. Perfect zoningB Dead simple commissioning.C. Wires are easier to run than ducts.D. More total holes in the walls. (Bad)E. Inherent frost protection.

12 comments:

I did a quick thought experiment on the issue:In a Pretty Good House (PGH), total airflow would be nearly double if the two fans are "fighting" each other instead of synchronized. That's because a PGH isn't nearly tight enough to prevent these fans from pushing and pulling 64 cfm through its walls and ceiling.Q. But isn't all that flow is coming through cracks in the house?A. Yes.Q. Doesn't that affect the amount of heat recovery?A. Probably not, because the materials in the walls act as a regenerative heat exchanger when subjected to a cycling air flow regime.Q. Isn't that 64 cfm going to cause problems in the walls?A. No. It's only 64 cfm. In a PGH, that much air cruises through whenever it gets slightly windy. But when it's forced and cycled, at least you get that fresh air where you want it (bedrooms), when you want it (while sleeping).

Pairs? Is'nt this unit doing intake and exhaust through the same unit? The newest Lumos unit does just that, and I thought that was what this knock-off was doing since it was not sold in pairs. But you are saying no that this is a single direction reversing unit?

If you build a tight house, the air can get unhealthy inside. Therefore you need ventilation. In the winter, ventilation air is cold, and this device uses the heat contained in the outgoing air to preheat the incoming fresh air.http://www.popularmechanics.com/home/improvement/interior/1275121

I used to live on the eastern plains of CO and now moved to central KS. I am building a 3,500 ft2 house and was thinking of using these units instead of a whole house unit (mainly because I don't trust the installers around here). I will have five bedrooms. Do you think I need one in each bedroom, or could I just put two on each floor? Thanks.

About Me

He received a BS in Engineering Physics from the Colorado School of Mines in 1977. During the country's first Solar Era, he received an MS in Mechanical Engineering and Solar Technology from CSU (1979) After involvement in hundreds of solar thermal systems in the early 80's, he received several product design patents. The focus of this blog is low and zero energy home design and construction for Denver.